GHK-Cu: structure and analysis

What it is

GHK-Cu is the tripeptide glycyl-L-histidyl-L-lysine in complex with a copper(II) ion. The peptide portion is three residues; the copper is coordinated to it rather than covalently bonded, held by the histidine imidazole and the peptide backbone nitrogen atoms.

The complex is characteristically blue in solution, which is a direct consequence of the coordinated copper — a visible property that no purely organic peptide in this catalogue has.

It is supplied at 50 mg and 100 mg, the largest fill weights in the catalogue.

How it is produced

Assembled by solid-phase peptide synthesis: the chain is built one residue at a time on an insoluble resin support, then cleaved from the resin, deprotected and purified — most commonly by reversed-phase high-performance liquid chromatography. The purified material is lyophilized to a dry solid.

The impurity profile that appears on a certificate is a record of where that process was imperfect: deletion sequences from an incomplete coupling, truncated chains, and species retaining a protecting group.

Confirming identity

Identity here has two parts rather than one, which is unusual in this catalogue. Mass spectrometry confirms the tripeptide sequence, and the copper content confirms the complex actually formed at the intended stoichiometry.

A vial containing the correct tripeptide but insufficient copper is not GHK-Cu — it is GHK. That distinction is invisible to a peptide purity measurement and requires elemental analysis to detect.

Analytical considerations

Copper is a specification to be met here, not an impurity to be minimised. This inverts how a heavy-metal result on a certificate should be read: for every other compound in the catalogue, copper would be a contaminant, and for this one a copper figure below specification is a failure of the material.

The complexed metal also complicates chromatography. Copper can interact with the stationary phase and with residual metal in the instrument path, so a method for GHK-Cu has to account for the complex remaining intact — or deliberately not — through the separation.

As a tripeptide it is small and polar, so it is weakly retained under reversed-phase conditions for the same reasons KPV and Epitalon are.

What its certificate reports

A certificate for a lot of this material names the lot, names the issuing laboratory, and states for each parameter both the method used and the specification the result was measured against. Identity and purity are the two core results; net peptide content states how much of the fill weight is actually peptide.

A certificate belongs to a lot, not to a product line. When a new lot is released it is tested again, and the certificate published against it is that lot's certificate — a previous lot's result is never carried forward.

Research use only

This page describes structure and analysis. It makes no claim about what this compound does, and none should be inferred from it. Material is supplied for laboratory research use only: it is not a drug, food, dietary supplement, cosmetic or medical device, it is not for human or veterinary consumption, and no dosing, administration or reconstitution guidance is provided for any such use.